The present invention relates generally to the field of underground boring and, more particularly, to underground sensing at a cutting tool using down-hole radar.
Utility lines for water, electricity, gas, telephone and cable television are often run underground for reasons of safety and aesthetics. In many situations, the underground utilities can be buried in a trench which is then back-filled. Although useful in areas of new construction, the burial of utilities in a trench has certain disadvantages. In areas supporting existing construction, a trench can cause serious disturbance to structures or roadways. Further, there is a high probability that digging a trench may damage previously buried utilities, and that structures or roadways disturbed by digging the trench are rarely restored to their original condition. Also, an open trench poses a danger of injury to workers and passersby.
The general technique of boring a horizontal underground hole has recently been developed in order to overcome the disadvantages described above, as well as others unaddressed when employing conventional trenching techniques. In accordance with such a general horizontal boring technique, also known as microtunnelling, horizontal directional drilling (HDD) or trenchless underground boring, a boring system is situated on the ground surface and drills a hole into the ground at an oblique angle with respect to the ground surface. A drilling fluid is typically flowed through the drill string, over the boring tool, and back up the borehole in order to remove cuttings and dirt. After the boring tool reaches a desired depth, the tool is then directed along a substantially horizontal path to create a horizontal borehole. After the desired length of borehole has been obtained, the tool is then directed upwards to break through to the surface. A reamer is then attached to the drill string which is pulled back through the borehole, thus reaming out the borehole to a larger diameter. It is common to attach a utility line or other conduit to the reaming tool so that it is dragged through the borehole along with the reamer.
In order to provide for the location of a boring tool while underground, a conventional approach involves the incorporation of an active sonde disposed within the boring tool, typically in the form of a magnetic field generating apparatus that generates a magnetic field. A receiver is typically placed above the ground surface to detect the presence of the magnetic field emanating from the boring tool. The receiver is typically incorporated into a hand-held scanning apparatus, not unlike a metal detector, which is often referred to as a locator. The boring tool is typically advance by a single drill rod length after which boring activity is temporarily halted. An operator then scans an area above the boring tool with the locator in an attempt to detect the magnetic field produced by the active sonde situated within the boring tool. The boring operation remains halted for a period of time during which the boring tool data is obtained and evaluated. The operator carrying the locator typically provides the operator of the boring machine with verbal instructions in order to maintain the boring tool on the intended course.
It can be appreciated that present methods of detecting and controlling boring tool movement along a desired underground path is cumbersome, fraught with inaccuracies, and require repeated halting of boring operations. Moreover, the inherent delay resulting from verbal communication of course change instructions between the operator of the locator and the boring machine operator may compromise tunneling accuracies and safety of the tunneling effort. By way of example, it is often difficult to detect the presence of buried objects and utilities before and during tunneling operations. In general, conventional boring systems are unable to quickly respond to needed boring tool direction changes and productivity adjustments, which are often needed when a buried obstruction is detected or changing soil conditions are encountered.
During conventional horizontal and vertical drilling system operations, the skilled operator is relied upon to interpret data gathered by various down-hole information sensors, modify appropriate controls in view of acquired down-hole data, and cooperate with other operators typically using verbal communication in order to accomplish a given drilling task both safely and productively. In this regard, such conventional drilling systems employ an xe2x80x9copenloopxe2x80x9d control scheme by which the communication of information concerning the status of the drill head and the conversion of such drill head status information to drilling machine control signals for effecting desired changes in drilling activities requires the presence and intervention of an operator at several points within the control loop. Such dependency on human intervention within the control loop of a drilling system generally decreases overall excavation productivity, increases the delay time to effect necessary changes in drilling system activity in response to acquired drilling machine and drill head sensor information, and increases the risk of injury to operators and the likelihood of operator error.
There exists a need in the excavation industry for an apparatus and methodology for controlling an underground boring tool and boring machine with greater responsiveness and accuracy than is currently attainable given the present state of the technology. There exists a further need for such an apparatus and methodology that may be employed in vertical and horizontal drilling applications. The present invention fulfills these and other needs.
The present invention is directed to systems and methods for down-hole sensing using radar. According to one embodiment, an underground drilling device is implemented for use with an above-ground locator. The underground drilling device includes a cutting tool assembly comprising a cutting tool and a sensor housing. A radar unit is provided in the sensor housing. A transmitter is also provided in the sensor housing. A processor, provided in the sensor housing and communicatively coupled to the radar unit and the transmitter, receives radar data from the radar unit and produces sensor data for transmission via the transmitter in a form suitable for reception by the above-ground locator.
According to another embodiment, a method of sensing at an underground drilling device in communication with an above-ground locator involves transmitting a radar probe signal from the underground drilling device. A radar return signal is received at the underground drilling device. The radar return signal is processed at the underground drilling device to produce sensor data. The sensor data is transmitted in a form suitable for reception by the above-ground locator.
The above summary of the present invention is not intended to describe each embodiment or every implementation of the present invention. Advantages and attainments, together with a more complete understanding of the invention, will become apparent and appreciated by referring to the following detailed description and claims taken in conjunction with the accompanying drawings.